//用两个栈实现一个队列。队列的声明如下，请实现它的两个函数 appendTail 和 deleteHead ，分别完成在队列尾部插入整数和在队列头部删除整数的
//功能。(若队列中没有元素，deleteHead 操作返回 -1 ) 
//
// 
//
// 示例 1： 
//
// 
//输入：
//["CQueue","appendTail","deleteHead","deleteHead","deleteHead"]
//[[],[3],[],[],[]]
//输出：[null,null,3,-1,-1]
// 
//
// 示例 2： 
//
// 
//输入：
//["CQueue","deleteHead","appendTail","appendTail","deleteHead","deleteHead"]
//[[],[],[5],[2],[],[]]
//输出：[null,-1,null,null,5,2]
// 
//
// 提示： 
//
// 
// 1 <= values <= 10000 
// 最多会对 appendTail、deleteHead 进行 10000 次调用 
// 
//
// Related Topics 栈 设计 队列 👍 715 👎 0


package leetcode.editor.cn;

// [剑指 Offer 09]用两个栈实现队列

import java.util.Stack;

public class YongLiangGeZhanShiXianDuiLieLcof_JianZhiOffer09 {
    public static void main(String[] args) {
        CQueue solution = new YongLiangGeZhanShiXianDuiLieLcof_JianZhiOffer09().new CQueue();
    }

    //leetcode submit region begin(Prohibit modification and deletion)
    class CQueue {
        private Stack inStack;
        private Stack outStack;

        public CQueue() {
            inStack = new Stack();
            outStack = new Stack();
        }

        public void appendTail(int value) {
            inStack.push(value);
        }

        public int deleteHead() {
            if (inStack.isEmpty() && outStack.isEmpty()) {
                return -1;
            } else if (outStack.isEmpty()) {
                in2out();
            }
            return (int) outStack.pop();
        }

        public void in2out() {
            while (!inStack.isEmpty()) {
                outStack.push(inStack.pop());
            }
        }

    }

/**
 * Your CQueue object will be instantiated and called as such:
 * CQueue obj = new CQueue();
 * obj.appendTail(value);
 * int param_2 = obj.deleteHead();
 */
//leetcode submit region end(Prohibit modification and deletion)

}